There are many things we’ve come to expect from our computer printers: photos, letters, greeting cards, maybe even glowing wallpaper someday. But muscle and bone? You wouldn’t have gone there until this week, when scientists at Carnegie Mellon announced they have developed a printer that outputs in “bio-ink”—a format they hope will pave the way for important organization and growth of stem cells.

In development for the past eight years, the printer is similar to a conventional ink jet, but with a custom-built nozzle designed to print patterns more accurately. The machine prints in bio-ink, solutions of hormones that alter cell behavior,  to create a blueprint for cells to grow and differentiate into the various types that scientists want to create, according to Dr. Julie A. Phillippi. She has worked on the project for about a year and a half.

“We loaded the bio-inks and  then printed square patterns of the bone bio-ink on a glass slide,” says Phillippi. “Then we placed the slide with the patterns in a dish with muscle-derived stem cells from adult mice. The cells growing on the bone bio-ink pattern began to exhibit characteristics of bone-like cells, and cells outside the pattern began to look like muscle cells.”

The scientists use a software program, designed in-house, to create the patterns. “The inkjet is ideal for what we’re trying to do because it allows for precise control over size, shape and concentration of the bio-ink patterns,” says Phillippi. The team is currently developing a 3D printer that consists of multiple print heads and delivers gel-like proteins as well as growth factors to build 3D patterns layer-by-layer.

The printed bio-ink patterns have applications in tissue regeneration, Phillippi insists, including using adult stem cells to treat tissue defects. “Through such a patterning approach, our vision is to heal patients with defects that span multiple tissue types using the patient’s own stem cells,” she says. –Erin McCarthy